For the first mentioned sequences based on fonts, what's the first number in the sequence that has less digits than the previous number?

It looks like that never occurs for Helvetica (A316600) due to the absence of kerning. However, with Arial (A316599) the description notes:

> a(29368) = 111111 is a first notable anomaly, because its bounding box width of 2675 lies between those of a(29367) = 49115, with bounding box width 2655, and a(29369) = 70002, with bounding box width 2681.